Homework assignments posted here are subject to correction in class or
through other means. Problems as assigned here are for your convenience
but are not a substitute for obtaining assignments in class.

1. Watch the 30 minute video
Ethics in Action: The
Tradition of the Engineering Profession 2.
Read the attached material on the Challenger Accident and the news articles
regarding a relatively recent issue associated with a shuttle launch. In a
well written essay, discuss the role the accident might have played in the
decision making process on whether to launch Endeavour, or if you choose, in
the Columbia disaster. You should also discuss how the Code of Ethics
applies to the decision-making process made by NASA. Grading for your
submission will be 75% on content and 25% on
grammar/spelling/punctuation/style. You should consider the objectives for
this assignment in composing your essay.

You should attempt to
watch this movie as soon as possible to allow time to rectify any problems
with distribution. You will only be able to watch this video from UK
Engineering machines on campus.

2. Read the handout from Chemical Engineering Progress,
"Engineering Ethics: What are the Right Choices?". Complete the
survey on the last page and be prepared to discuss in class. You will submit
this survey anonymously after the discussion. Participation in the discussion
will be noted as part of your course grade.

Assignment Learning Objectives:

Explain the role the code of ethics plays in engineering decision-making

Explain the benefits of ethical practices in engineering

Apply the code of ethics to realistic scenarios in an appropriate manner

Problems for submission:
3. 2-27 (note that in Table 2-5, the causative
variable for this scenario is the dose V in equation 2-5)
4. What is the concentration in mg/m3 of 7 ppm of carbon tetrachloride
(aq)?
5. What is the concentration in mg/m3 of 25 ppm of ammonia (v)?

Assignment Learning Objectives:

Locate and interpret documentation expressing the toxicity of substances

In-class Problems
10-9, 10-16, 10-17
P-1. Why should block valves that isolate pressure safety relief valves be
inspected monthly to ensure they are sealed in an open position?

Problems for submission
10-8, 10-11, 10-22
P-2. An operating plant normally requires city water for a wide variety of uses.
Some of these required uses at a plant include a drinking fountain, a safety
shower, a chemical reactor, and an eyewash station. Should the chemical reactor
overpressure, how could you ensure the integrity of the water supply to the
drinking fountain, safety shower, eyewash station, and city water supply main?
Draw a schematic diagram explaining your plan.

Background: Most combustion reactions occur in the gas phase. In order
for any flammable material to burn, there must be both fuel and oxidizer
present. There must also be a minimum concentration of the flammable gas or
vapor in the oxidizer. For most fires to occur, a minimum fuel concentration
must exist in air at ambient temperature. The minimum concentration at which
ignition will occur is called the lower flammability limit (LFL). If the
flammable material is normally liquid, the liquid must e warm enough to provide
a vapor-air mixture equal in fuel concentration to the LFL concentration. The
liquid temperature at which the vapor concentration reaches the LFL can be found
experimentally. It is usually measured using a standard method called a "closed
cup flash point" test. The "flash point" of a liquid fuel is thus the liquid
temperature at which the concentration of fuel vapor in air is large enough for
a flame to flash across the surface of the fuel if an ignition source is
present.
The flash point and the LFL concentration are closely related through the vapor
pressure of the liquid. Thus, if the flash point is known, the LFL concentration
can be estimated; and if the LFL concentration is known, the flash point can e
estimated. In most cases, the calculation can be made for pure liquids using
Raoult's law. However, if the liquid is a mixture, particularly one where the
components are dissimilar, the liquid solution may be non-ideal. Then the liquid
phase activity coefficients may need to be determined in an accurate estimate of
the relationship between flash point and LFL is to be made. The system total
pressure is ambient, so it is low enough for the vapor (or gas) phase above the
liquid surface to be considered ideal.

Problem: Estimate the flash point of a mixture made by
mixing 600 ml of methanol and 400 ml of water. The solution is not ideal, and
the activity coefficients must be estimated. For the estimation of activity
coefficients, first determine the activity coefficients for methanol-water
solutions from vapor liquid equilibrium data. Assume that the activity
coefficients are function of composition only, and do not depend on the system
pressure and temperature. Is such an assumption justified? Vapor liquid
equilibrium data can be found in Perry's Chemical Engineers' Handbook.
Vapor pressure data can be found in the Handbook as well. The LFL of
methanol can be found in NFPA 325M, Properties of Flammable Liquids or
Sax's Dangerous Properties of Industrial Materials. Once the mixture is
ignited, will it continue to burn?

1. The liquid level in a tank 10 meters in height is determined by measuring
the pressure at the bottom of the tank. The level gauge was calibrated to work
with a liquid having a specific gravity of 0.9. If the usual liquid is replaced
with a new liquid with a specific gravity of 0.8, will the tank be overfilled or
underfilled? If the actual liquid level is 8 meters, what is the reading on the
level gauge? Is it possible that the tank will overflow without the level gauge
indicating the situation?

2. Large storage tanks are only capable of withstanding very low pressures or
vacuums. Typically they are constructed to withstand no more than 20.3 cm of
water gauge pressure and 6.3 cm of water gauge vacuum.

A
particular tank is 10-m in diameter.

a)

If an 80 kg person stands in the
middle of the tank roof, what is the resulting pressure (in Pa) if the person's
weight is distributed across the entire roof?

b)

If the roof were flooded with
20.3 cm of water (equivalent to the maximum pressure),
what is the total weight (in kg) of the water?

Background: There are many occasions when the thrust
forces caused by high velocity, high rate flow will cause excessive forces on
piping and associated equipment. Sometimes the design of relatively simple
devices can be complicated by the possibility of severe mechanical loads on
piping equipment. If proper precautions are not taken to prevent failure due to
these forces, then very serious accidents can occur.

Some examples of such situations might be in the design of
safety relive systems wherein there exists the possibility of suddenly
initiated, very high velocity flow, with the consequent possibility of the
discharge piping reacting with significant movement, as for example, after the
manner of a garden hose that is not being held. Our experience tells us that the
hose will move erratically about, discharging water in many directions. One
should be aware that even heavy steel piping can behave similarly if it is not
suitably constrained.

Another serious situation can develop from misuse of a rather
common item that exits in laboratories, perhaps in laboratories where you have
worked. This is the compressed gas cylinder. A typical situation might exist at
your gas chromatograph, for example, where air is being used in conjunction with
hydrogen, in the flame ionization detector. The air is usually supplied at a
pressure in excess of 2000 lb/in2. If the cylinder is not properly restrained
and held, it can be easily knocked over with possibly disastrous results if the
valve is broken off in the fall.

The result of unexpectedly high thrust forces from flow may
frequently be disastrous because of the rapid, violent, and unpredictable motion
of a pipe, or as in the example above, a rather heavy gas cylinder. There is
also the distinct possibility of equipment failure from the forces which would
result in the discharge of dangerous materials to the air.

In this problem, you are asked to estimate some forces, the
magnitude of which might easily cause equipment failure with the consequent loss
of large quantities of a highly flammable material to the air. The result would
almost certainly be a serious gas cloud explosion and fire.

Problem: A tank ship hauling Liquefied Natural Gas (LNG)
is being unloaded into a 600,000 bbl storage tank at a rate of 55,000 gal/min
through a 30-in. diameter, schedule 10 stainless steel pipe. The schematic
diagram of the pipe inside the tank is shown on the next page. Determine the
total upward force on the tank roof and the horizontal and vertical forces on
the splash plate.

Background: Most chemical manufacturing operations involve the
generation, use, and disposal of substances that are hazardous because of their
toxicity or flammability. In many cases, the hazardous substance is a chemical
that is widely used and not considered dangerous. For example, common salt is
used in many processes without causing any particular problems with toxicity.
However, if salt is contained in water that is discharged to streams, it may
cause irreversible damage to the environment, including both plant and animal
life. Thus, while salt is not a particularly hazardous material to handle and to
use in processing, it must be kept out of the water that is discharged from a
plant. Other substances may be much more toxic, of course, and the must be kept
from the environment as well.

The nature of the substances and their effects on the environment are
sometimes known quite well, but sometimes it is only known that they have a
toxic effect. Sometimes the toxic effects are inferred for one material through
comparison with another similar material. For example, if we know that high
concentrations of sodium chloride are toxic to certain plants in the ecosystem,
we can infer that high concentrations of potassium chloride will also be toxic
to the same plants. (Of course, we much keep in mind that the same substances my
be required for life. Sodium and potassium salts are necessary for proper cell
growth and reproduction; and potassium deficiencies in particular are
encountered in nature. We frequent add potassium salts in the form of
fertilizers to enhance plant growth.)

We cannot add large quantities of most substances to the ecosystem without
damage. Thus, the kind and amount of materials present in water streams
discharged from a plant must be closely monitored to make certain that the
discharged water will be within the quality standards specified by the
Environmental Protection Agency. The standards for the purity of discharged
water depend on the substances in the water and the potential damage to the
environment. Specific concentrations can be obtained from the Environmental
Protection Agency.

The specific method used to remove hazardous substances from water depends on
the nature of the hazardous substance and the concentrations involved. Several
different methods can be used. The following problem illustrates one method that
might be used.

Problem: The
water used in a chemical processing plant contains a mixture of organic acids.
The acids are not particularly toxic to the environment in small concentrations,
but the concentration in the process water stream is 0.5% by weight leaving the
process, and that concentration is too large for discharge. The acids cannot be
used in the plant for any other purpose, and there is insufficient acid for
their recovery, purification, and sale. The acids are soluble in hydrocarbons,
and it is decided to extract the acids from the water streams by countercurrent
liquid-liquid extraction, then use the hydrocarbon as a fuel for one of the
plant process heaters. There is no chlorine, nitrogen, or sulfur in the acids,
so when are burned with the fuel, They will not contribute any additional
pollution to the air. The hydrocarbon used for the extraction is the fuel oil
for the process heaters. Equilibrium data for the acid-water-oil system are
given in the table below. Plot the data on a triangular diagram or use the
McCabe Thiele approach and plot mass ratios of acid to solvent. Determine how
much oil will be required to reduce the concentration of acid from the 0.5 mass
percent in the feed to 0.05 mass percent, which has been found to be acceptable
for discharge. The oil rate used in the process will be 1.5 times the minimum,
and the water to be treated will enter the extraction system at a rate of 3500
gallons per day. The oil has a specific gravity of 0.88. Assume the process is
to be performed in a countercurrent liquid-liquid extractor having an overall
efficiency of 20%. How many stages will be required for the extractor?